In recent years, there has been an increasing interest in producing semiconductor-on-insulator (SOI) wafers for use as semiconductor substrates for the formation of integrated circuits. One method of forming an SOI substrate is by the use of the separation by implantation of oxygen (SIMOX) process. One step in the SIMOX process comprises the implantation of oxygen using a high current oxygen implanter that introduces oxygen beneath the surface of the substrate to create the buried semiconductor oxide layer. A later annealing step is used to repair implant damage performed during the implant process and to react the buried oxygen atoms with semiconductor atoms to form the buried oxide layer. SOI wafers formed using this process enjoy a variety of advantages over wafers comprising bulk semiconductor material. The quality of the SOI substrate formed using the SIMOX process is dependant on the temperature of the wafer during the process and the uniformity of the implantation across the wafer.